Dynamo action in planetesimals

星子中的发电机作用

• 批准号: 169827976
• 负责人: Professor Dr. Andreas Tilgner
• 金额: --
• 依托单位: Leibniz-Institut für Astrophysik Potsdam (AIP)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/169827976?language=en
• 关键词: Dynamo; action; planetesimals

Recent measurements of remanent magnetization in meteorites showed that the field strengths are probably incompatible with ambient field capture or impact-generated fields. The proposed mechanism for the generation of magnetic fields in meteoritic material that has formed in planetesimals is a hydromagnetic dynamo. It was also shown that fluid material must have been present in a large variety of bodies in the early Solar System. The proposed project aims at the investigation of dynamo action in planetesimals. One of the generators may be convection driven by radioactivity or chemical differentiation of the melt, providing heat sources for a few million years. Another possible dynamo mechanism may employ the nutation-driven flows in the bodies, assuming that most planetesimals had nonspherical shapes. An extreme form of dynamo with forcing on the surface could be a collisional dynamo where external, abrupt changes of the rotation axis lead to topology changes of the magnetic fields, possibly exciting a dynamo in minor bodies of the Solar System. The existence of the latter dynamo is yet to be shown theoretically. If no dynamo is found, but the field is simply amplified by differential rotation, magnetic instabilities will be important for the magnetisation of those parts of the planetesimal which had already solidified.

在陨石中对远程磁化的最新测量表明，该场强可能与环境场捕获或冲击生成的田地不相容。在行星模拟中形成的陨石材料中产生磁场的提议的机制是一种水力磁发电机。还表明，早期太阳系中的各种物体中必须存在流体材料。拟议的项目旨在调查行星中的发电机作用。其中一个发电机可能是由熔体的放射性或化学分化驱动的对流，提供了数百万年的热源。假设大多数行星都具有非球形形状，则可能采用了人体中的营养驱动的流动。在表面上强迫的一种极端形式的发电机可能是碰撞的发电机，其中旋转轴的外部，突然的变化导致磁场的拓扑变化，可能会激发太阳系次要体内的发电机。后一种发电机的存在尚未在理论上显示。如果找不到发电机，但是仅通过差异旋转而放大了场，那么磁性不稳定性对于已经固化的地球上那些部分的磁性很重要。